Modulation system



Feb. 6, 1934.A R D DUNCAN, JR 1,945,630

MODULAT ION SYSTEM Filed May 5, 1932 lEf-l wlzrllnlulllllla.

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5f m if f? ff@ n l /Z m INVENTOR Ruinart 1]. Hannan, Jr.

Patented Feb. Ei, 1934 NETE@ STATES PATENT `GEW'CE MODULATON SYSTEM Application May 5, 1932. Serial No. 609,358

7 Claims.

My invention pertains in general to radiosignaling and specifically relates to a system for modulating high frequency energy.

One of the objects of my invention consists in providing a modulation system having a special type of space discharge tube in which the electronic discharge is controlled by both an electrostatic field and an electromagnetic eld.

Another object consists in producing a mcdu lation system in which variable electrical energy at one frequency electrostatically controls an electronic stream while variable electrical energy at a different frequency electromagnetically controls the same electronic stream.

A further object comprises providing a modulation system in which a source of variable electrical energy is connected at one point of a control grid in a space discharge tube and to a catrcde of a space discharge tube to produce an electrostatic field while another source of variable electrical energy is connected across two points of the same control grid to produce a-n electromagnetic field.

I accomplish the above desirable objects in a novel type of modulation system employing a space discharge tube having a helical control electrede to which are connected two different sources of variable electrical energy to produce both an electrostatic eld and an electromagnetic field.

In the drawing accompanying and forming a part of this specication and in which like reference numerals designate corresponding parts throughout Fig. i is a transverse sectional view of one embodiment of the space discharge tube employed in my invention; and

Fig. 2 is a diagrammatic representation of the modulation system of my invention employing the space discharge tube of Fig. l.

My invention contemplates providing a system for amplifying sustained high frequency oscillations and at the same time modulating these oscillations in accordance with variable electrical energy such as audio frequency voice currents, According to my invention this is accomplished by providing a special type of space discharge tube in which the electronic discharge is under control of both an electrostatic field and an electromagnetic eld which are respectively produced by two dierent sources of variable electrical energy. In the apparatus of my system the space discharge tube is provided with a cylindrical anode having an axial electron emissive cathode and a co-axial helical control electrode. This control electrode is adapted to produce both an electromagnetic field and an electrostatic field by virtue of connections to diilerent sources of variable electrical energy.

Referring to the drawing in detail, and particuy larly to Fig. 1, a cylindrical metallic anode 2 is 60l provided within a substantially cylindrical envelope l. The envelope 1 is composed of a suitable material such as glass or fused quartz and is evacuated to produce a pressure conducive to l' electronic discharge. The anode 2 is secured be- 65 tween a press 3 and a press 4 in opposite sides of the containing envelope 1. A terminal lead 5 is connected to the anode 2 and extends through the envelope l for making connections with extery nal circuits. A catho-de 6 comprising an electron 70" emissive filament is provided between the-pressesv 3 and 4 axially of the cylindrical anodel 2. The cathode 6 has portions extending exteriorly of the envelope 1 for making connections with an external circuit.

A helical control electrode 7 is positioned between the press 3 and the press 4 co-axially or the cylindrical anode 2. The control electrode 7, by virtue of its helical construction, is adapted to produce an electromagnetic eld. The con- 80' trol electrode 7 is provided with terminal leads 8 and 9 extending through the press 3 and the press 4, respectively, for making connections with an external circuit.

Referring to Fig. 2, the control electrode 7 is 85-v connected in series with an inductance 10 through terminal leads 8 and 9. The inductance 10 is electromagnetically coupled to an inductance 11 which is connected through a source of electrical y energy 12 to a microphone 13. The microphone 90Y 13 and source of electrical energy 12 are indicative of means for producing modulation energy.

It will, of course, be understood that any other desirable means for producing modulation energy, such as a television scanning system, may be 95 equally well employed without departing from the intended scope of my invention.

The anode 2 is connected through an inductance 14 and source of high potential electrical energy 15 to the cathode 6. A source of electri- 100 cal energy 16 is connected to the cathode 6, as shown, to heat the same to an electron emissive temperature. The inductance 14 is electromagnetically coupled to another inductance 17 connected to the terminals 18. The inductance 14 105 and terminals 18 are indicative of a work circuit for the utilization of modulated high frequency energy.

A source of sustained high frequency oscillations 19 is connected between the terminal lead 110 9 of the control electrode 7 and the cathode 6. The source 19 can be any organization for producing high frequency energy such as a space discharge tube oscillator or an alternator.

In the operation of my modulation system the source of high frequency energy 19 produces electrostatic charges upon the control electrode l which correspondingly control the space current between the anode 2 and cathode 6 to produce amplified high frequency energy in the inductance 14. Acoustical vibrations incident upon the microphone 13 will act through the source of electrical energy 12 and inductance 11 to induce electromotive forces in the inductance 10 which will cause the helical control electrode 7 to set up an electromagnetic field. The electromagnetic field produced by the control electrode 7 will Vary in intensity with the modulation energy under control of the microphone 13. At the same time, the electrostatic field produced by the control electrode '7 will vary in intensity in accordance with the oscillations produced by the source 19. It will be obvious that the electronic discharge from the cathode 6 to the anode 2 will be under control of both the electrostatic field and the electromagnetic field to produce modulated high frequency energy which will be available at the terminals 18 for any desirable use such as for radiation in radiosignaling.

It will, of course, be understood that the source of oscillations 19 could be connected to the control electrode 7 to produce an electromagnetic field, while the source of modulation energy acting through inductance 10 could be connected to the control electrode 7 to produce an electrostatic field. It will, of course, be further understood that other changes will readily occur to those skilled in the art but which will not depart from the intended scope of my invention. I do not, therefore, desire to limit myself to the foregoing except insofar as may be pointed out in the appended claims.

What I claim as new and original and desire to secure by Letters Patent ofthe United States 1. A modulation system comprising, a space discharge tube having an anode and a cathode for producing an electronic stream, a control electrode positioned between said cathode and anode for producing both an electrostatic field and an electromagnetic eld, a source of Variable electrical energy for producing said electrostatic eld, and a second source of variable electrical energy connected between two points of said control electrode for producing by current 'flow through said control electrode said electromagnetic field.

2. A modulation system comprising, a space discharge tube having a cathode and an anode for producing an electronic stream, a control electrode in said space discharge tube for producing both an electromagnetic field and an electrostatic field, a source of variable electrical energy connected between said control electrode and said cathode for producing said electrostatic field, and a second source of electrical energy connected between two different points of said control electrode for producing by current iow therethrough said electromagnetic field.

3. A modulation system comprising, a space discharge tube having an anode and cathode for producing an electronic stream, a helically formed control electrode disposed between said cathode and anode, a source of variable electrical energy connected to two points of said control electrode for producing by current ow therethrough an electromagnetic field and a second source of variable electrical energy connected to said control electrode for producing an electrostatic field.

e. A modulation system comprising, a space discharge tube having a substantially cylindrical anode and a cathode disposed internally of said anode for producing an electronic stream, a helically formed control electrode disposed between said cathode and said anode, a source of variable electrical energy connected to said control electiode for producing an electrostatic field to control said electronic stream, and a second source of electrical energy connected to two points of said control electrode for producing by current flow therethrough an electromagnetic field to control said electronic stream.

5. A modulation system comprising, a space discharge tube having a substantially cylindrical anode and a cathode internally disposed of said anode for producing an electronic stream, a helicaily formed control electrode disposed between said cathode and said anode, a source of steady potential electrical energy connected between said cathode and said anode, a source of variable electrical energy connected between said control electrode and said cathode for producing an electrostatic field to control said electronic stream, another source of variable electrical energy con-` nected with two points of said helically formed control electrode to produce an electromagnetic field to control said electronic stream.

6. A modulation system comprising, a space discharge tube having a substantially cylindrical anode and a cathode axially disposed thereof for producing an electronic stream, a helically formed control electrode positioned between said cathode and said anode, a source of steady potential electrical energy connected between said cathode and said anode, a source of variable electrical energy connected between said control electrode and said cathode for producing an electrostatic field to control said electronic stream, and a second source of variable electrical energy connected between two diiferent points of said control electrode for producing an electromagnetic eld to control said electronic stream.

7. A modulation system comprising, an envelope having an attenuated atmosphere, a substantially cylindrical anode disposed within said envelope, an electron emissive cathode disposed axially of said anode, a helically formed control electrode positioned between said cathode and said anode, a source of electrical energy for heating said cathode to an electron emissive temperature, a source of steady potential electrical energy connected between said cathode and anode, a source of variable electrical energy connected between said control electrode and said cathode for producing an electrostatic field to control said electronic stream, and another source of variable electrical energy connected between two different points of said control electrode to produce an electromagnetic eld to control said electronic 

